Cross-linked Elastomer Composition for UV-Resistant Seals
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Solution Overview
Problem
Existing elastomeric compositions for gaskets in automotive and building applications face challenges such as poor dimensional stability, high compression set, limited temperature range, and resistance to UV rays, while also requiring non-halogenated and aesthetically pleasing solutions.
Innovation Solution
A composition comprising a multiblock copolymer of ethylene and alpha-olefin, a styrene-ethylene/butylene-styrene (SEBS) or styrene-butadiene-styrene (SBS) block copolymer, and a crosslinkable polymer like polybutadiene, which provides improved UV resistance, low compression set, and a matte or satin appearance without the need for halogenated compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If halogenated compounds (PVC) are used to achieve good sealing properties and dimensional stability, then compression set is reduced, but harmful halogenated molecules are released during combustion and UV exposure
Solution Approach 1:
The invention extracts and removes harmful halogenated compounds from the composition entirely, replacing them with non-halogenated alternatives (ethylene/alpha-olefin multiblock copolymer, SEBS/SBS block copolymers, and crosslinkable polymers) that provide the same functional benefits without releasing harmful molecules during combustion or UV exposure
Solution Approach 2:
The invention uses a composite material system combining multiple non-halogenated polymers: a multiblock copolymer of ethylene and alpha-olefin (5-50 wt%), a block copolymer with aromatic blocks (SEBS or SBS, 3-50 wt%), and a crosslinkable polymer (polybutadiene or SBS, 3-50 wt%). This composite provides dimensional stability and compression resistance without halogenated compounds
2Reliability
If crosslinking is increased to reduce compression set and improve UV resistance, then durability is improved, but processing difficulty and manufacturing complexity increase
Solution Approach 1:
The invention changes the crosslinking parameter from heavy/high-crosslinking to moderate/controlled crosslinking by selecting crosslinkable polymers with appropriate reactivity (polybutadiene or SBS at 3-50 wt%) and controlling the crosslinking degree, thereby achieving sufficient UV resistance and low compression set while maintaining extrudability and processability
Solution Approach 2:
The composite material system combines crosslinkable polymers with non-crosslinking polymers (ethylene/alpha-olefin multiblock copolymer and SEBS/SBS block copolymers) to achieve balanced properties: the crosslinkable polymer provides UV resistance and low compression set, while the non-crosslinking polymers maintain flexibility and extrudability
3Object-generated harmful factors
If traditional elastomers (EPDM, TPE-V, TPE-S) are used to replace halogenated compositions, then halogen-free formulation is achieved, but colorability and surface appearance deteriorate
Solution Approach 1:
The invention uses a composite of three specific polymer types: multiblock copolymer of ethylene and alpha-olefin, block copolymer with aromatic blocks (SEBS or SBS), and crosslinkable polymer. This specific composite provides both halogen-free formulation and improved surface appearance with matte or satin finish, overcoming the appearance defects of traditional EPDM, TPE-V, and TPE-S elastomers
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves a balance of flexibility, UV resistance, and aesthetic appeal, making it suitable for a wide range of applications with improved durability and resistance to UV aging.
Implementation Method 1
a crosslinkable polymer, the crosslinkable polymer being a polybutadiene or a styrene-butadiene-styrene triblock copolymer (SBS)... The term 'crosslinkable polymer' is understood to mean a polymer whose macromolecules can bind together by a chemical reaction, occurring during a polymerization, a polycondensation or a polyaddition
Implementation Method 2
the block copolymer allows the formation of nodules of the aromatic blocks within the composition, while the elastomeric blocks will combine with the crosslinkable polymer and/or the multiblock copolymer of ethylene and alpha-olefin. At room temperature, the nodules, which have a glass transition temperature higher than room temperature, are then in the glassy state and therefore comparable to crosslinking nodes, which creates a physical pseudo-crosslinking
Implementation Method 3
The copolymer is a polymer which is particularly resistant to ultraviolet rays, and which exhibits permanent compression set (DRC) weak. It makes it possible in particular to limit aging, due to ultraviolet rays, of the composition, without requiring the addition of black pigments or other additives which reduce certain properties of the product
Data Source
AI summary
The invention relates to a cross-linked elastomer composition including: an ethylene/alpha-olefin multiblock copolymer comprising polymerized ethylene and alpha-olefin units, an elastomer including a block copolymer having at least two, identical or different, aromatic blocks which are separated by at least one elastomer block, and a cross-linkable polymer, for example, a diene elastomer. The invention also relates to a product including the composition, and to the use of such a product as a seal.